U.S. patent number 11,320,035 [Application Number 16/186,086] was granted by the patent office on 2022-05-03 for gear wheel, in particular idler gear, for a gear train.
This patent grant is currently assigned to MAN Truck & Bus AG. The grantee listed for this patent is MAN Truck & Bus AG. Invention is credited to Jens Tuerk, Marcus Viet.
United States Patent |
11,320,035 |
Tuerk , et al. |
May 3, 2022 |
Gear wheel, in particular idler gear, for a gear train
Abstract
A gear wheel, in particular an idler gear, for reducing backlash
in a gear train, includes a first wheel part and a second wheel
part. The first wheel part has multiple teeth that are distributed
over a periphery of the first wheel part. The first wheel part may
rotate about a first axis (A). The second wheel part has multiple
teeth that are distributed over a periphery of the second wheel
part. The second wheel part may rotate about a second axis (B) that
is arranged parallel to and offset with respect to the first
axis.
Inventors: |
Tuerk; Jens (Postbauer-Heng,
DE), Viet; Marcus (Hunfeld-Sargenzell,
DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
MAN Truck & Bus AG |
Munich |
N/A |
DE |
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|
Assignee: |
MAN Truck & Bus AG (Munich,
DE)
|
Family
ID: |
1000006281267 |
Appl.
No.: |
16/186,086 |
Filed: |
November 9, 2018 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190136955 A1 |
May 9, 2019 |
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Foreign Application Priority Data
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Nov 9, 2017 [DE] |
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102017126205.9 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16H
57/12 (20130101); F16H 1/20 (20130101); F16H
55/18 (20130101); F16H 2057/127 (20130101); F16H
2055/185 (20130101) |
Current International
Class: |
F16H
55/18 (20060101); F16H 1/20 (20060101); F16H
57/12 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10058482 |
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Jun 2002 |
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DE |
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20102749 |
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Jun 2002 |
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DE |
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102009015947 |
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Oct 2010 |
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DE |
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102009055214 |
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Jun 2011 |
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DE |
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102017113900 |
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Jan 2018 |
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DE |
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1559798 |
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Mar 1969 |
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FR |
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Other References
German Search report for related application No. DE 102017126205.9,
dated Jul. 26, 2018. cited by applicant .
European Search Report in related case No. EP 18203450.4, dated
Mar. 15, 2019. cited by applicant.
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Primary Examiner: Kelleher; William
Assistant Examiner: Prather; Gregory T
Attorney, Agent or Firm: Maginot, Moore & Beck LLP
Claims
The invention claimed is:
1. A gear wheel for reducing backlash and/or compensating for
backlash in a gear train, said gear wheel comprising: a first wheel
part having multiple teeth that are distributed over a periphery of
the first wheel part, wherein the first wheel part may rotate about
a first axis (A); a second wheel part having multiple teeth that
are distributed over a periphery of the second wheel part, wherein
the second wheel part may rotate about a second axis (B) that is
arranged parallel to and offset with respect to the first axis (A);
a first wheel stud about which the first wheel part is mounted in a
rotatable manner; and a second wheel stud about which the second
wheel part is mounted in a rotatable manner, wherein the first
wheel stud and the second wheel stud are fastened to one another in
an eccentric manner with respect to one another via a press fit
arrangement or a screw connection.
2. The gear wheel according to claim 1, wherein the second wheel
part may deform in regions in an elastic manner in a radial
direction in relation to the second axis (B); and/or the second
wheel part may rotate relative to the first wheel part.
3. The gear wheel according to claim 1, wherein: the second wheel
part comprises at least one gear wheel sheet, wherein the at least
one gear wheel sheet may deform in an elastic manner in a radial
direction in relation to the second axis (B).
4. The gear wheel according to claim 3, further comprising:
multiple gear wheel sheets arranged adjacent to one another and
forming a gear wheel sheet stack.
5. The gear wheel according to claim 3, wherein: the at least one
gear wheel sheet is produced from a spring steel.
6. The gear wheel according to claim 3, wherein the at least one
gear wheel sheet comprises at least one elongated hole, so as to
provide an elasticity of the second wheel part, wherein the at
least one elongated hole extends in a peripheral direction about
the second axis (B) in a circular and/or helical manner.
7. The gear wheel according to claim 1, further comprising: a first
plain bearing bush arranged between the first wheel stud and the
first wheel part; and a second plain bearing bush arranged between
the second wheel stud and the second wheel part.
8. The gear wheel of claim 1, wherein the gear wheel comprises an
idler gear.
9. A gear train for a motor vehicle, comprising: an idler gear
comprising a gear wheel having a first wheel part having multiple
teeth distributed over a periphery of the first wheel part, wherein
the first wheel part may rotate about a first axis (A); the gear
wheel further having a second wheel part having multiple teeth
distributed over a periphery of the second wheel part, wherein the
second wheel part may rotate about a second axis (B) that is
arranged parallel to and offset with respect to the first axis (A);
a drive wheel that meshes with the first wheel part of the idler
gear and the second wheel part of the idler gear; and an output
wheel that meshes with the first wheel part of the idler gear and
the second wheel part of the idler gear; wherein the second axis
(B) is arranged offset in relation to the first axis (A) in a
direction of an angle bisector in relation to an angle that is
defined between an axis of rotation of the drive wheel, of the
first axis (A) and an axis of rotation of the output wheel.
10. The gear train according to claim 9, wherein the gear wheel
further comprises: a first wheel stud about which the first wheel
part is mounted in a rotatable manner; and a second wheel stud
about which the second wheel part is mounted in a rotatable manner,
wherein the first wheel stud and the second wheel stud are fastened
to one another in an eccentric manner with respect to one another
via a press fit arrangement or a screw connection.
11. The gear train according to claim 9, wherein the second wheel
part of the idler gear is braced by trailing edges of the drive
wheel and by trailing edges of the output wheel in a direction with
respect to the second axis (B) in an elastic manner.
12. The gear train according to claim 9, wherein load flanks of the
drive wheel and load flanks of the output wheel are in engagement
with the first wheel part, and trailing edges of the drive wheel
and trailing edges of the output wheel are in engagement with the
second wheel part.
13. The gear train according to claim 9, wherein the multiple teeth
of the first wheel part contact load flanks of the drive gear wheel
and load flanks of the output gear wheel; and the multiple teeth of
the second wheel part contact trailing edges of the drive gear
wheel and trailing edges of the output gear wheel.
14. The gear train according to claim 9, wherein: a lifting of the
multiple teeth of the first wheel part from load flanks of the
drive wheel and from load flanks of the output wheel in the case of
a change of sign of the drive torque and/or the output torque
and/or in the case of torsional oscillations is counteracted by
means of bracing the second wheel part said bracing resulting from
the offset between the second axis (B) and the first axis (A) and
an elasticity of the second wheel part.
15. The gear train according to claim 9, further comprising: at
least one further output wheel that meshes with the idler gear; and
a further wheel part of the idler gear is provided for each of the
at least one further output wheel, said further wheel part being
embodied in each case corresponding to the second wheel part of the
idler gear.
16. A motor vehicle, comprising: a gear train having an idler gear
comprising a gear wheel having a first wheel part having multiple
teeth distributed over a periphery of the first wheel part, wherein
the first wheel part may rotate about a first axis (A); the gear
wheel further having a second wheel part having multiple teeth
distributed over a periphery of the second wheel part, wherein the
second wheel part may rotate about a second axis (B) that is
arranged parallel to and offset with respect to the first axis (A);
a drive wheel that meshes with the first wheel part of the idler
gear and the second wheel part of the idler gear; and an output
wheel that meshes with the first wheel part of the idler gear and
the second wheel part of the idler gear; wherein the second axis
(B) is arranged offset in relation to the first axis (A) in a
direction of an angle bisector in relation to an angle that is
defined between an axis of rotation of the drive wheel, of the
first axis (A) and an axis of rotation of the output wheel.
17. The motor vehicle of claim 16, further comprising: a compressor
for compressing air that is driven via the gear train.
18. The motor vehicle of claim 16, wherein the motor vehicle is a
commercial vehicle.
Description
The invention relates to a gear wheel, in particular an idler gear,
for reducing backlash in a gear train.
Gear drives that are exposed to greatly varying torques tend to
develop transmission rattle at low engine rotational speeds and
transmission whistle at high engine rotational speeds. This is
particularly pronounced when driving air compressors on engines of
commercial vehicles. Piston air compressors have the characteristic
that the sign of the torque reverses for a short time after
exceeding the upper dead centre by means of re-expansion. The
result is the tooth flanks hitting against one another and the
acoustic rattle that results therefrom.
DE 100 58 482 A1 proposes for this purpose a gear wheel for
absorbing angular momentum. Undesirable noises are avoided by
virtue of the fact that a gear wheel is formed from two wheel parts
that are connected via an elastomer in a torque-conducting manner.
In the disassembled state, the teeth of the wheel parts are rotated
against one another. After installing the gear wheel, the wheel
parts are rotated with respect to one another in such a manner that
the teeth almost align. This is achieved by virtue of the fact that
the teeth of a further gear wheel that meshes with the gear wheel
hold the teeth of the wheel parts in this position. By virtue of
the elastomer, the rotation and the self-aligning torque that
results therefrom produces a permanent prestressing arrangement
with the result that the tooth flanks of the wheel parts and the
gear wheel that meshes with said tooth flanks are always in
positive-locking contact. In the case of gear trains in which two
gear wheels are in engagement, the function is fully provided when
used at the drive wheel or the output wheel. In the case of gear
trains in which three gear wheels are in engagement and in which
the multi-part gear wheel is used as an idler gear, the function is
no longer entirely provided. It may be conceptionally
disadvantageous at the divided gear wheel that said gear wheel only
absorbs the effects.
The object of the invention is to provide an alternative or
improved gear wheel for a gear train, said gear wheel rendering it
possible when being used in particular as an idler gear to
effectively reduce or compensate for backlash. In particular, as an
idler gear it is therefore to provide the possibility of reducing
or compensating the backlash at a driving wheel and a driven wheel
via the idler gear.
The object is achieved by virtue of a gear wheel and a gear train
in accordance with the independent claims. Advantageous further
developments are disclosed in the dependent claims and the
description.
The gear wheel may be in particular an idler gear. The gear wheel
is suitable for reducing backlash and/or for compensating for
backlash in a gear train. The gear wheel comprises a first wheel
part having multiple teeth that are distributed over a periphery of
the first wheel part. The first wheel part may rotate about a first
axis. The gear wheel comprises a second wheel part having multiple
teeth that are distributed over a periphery of the second wheel
part. The second wheel part may rotate about a second axis that is
arranged parallel to and offset with respect to the first axis.
The parallel arrangement of the first axis and the second axis
causes the second wheel part to be mounted in an eccentric manner
with respect to the first wheel part. The centre of rotation of the
first wheel part and the centre of rotation of the second wheel
part are offset in the installed state in a radial direction by the
distance of the first axis with respect to the second axis. As a
consequence, an offset arrangement may be produced in the
peripheral direction between the multiple teeth of the first wheel
part and the multiple teeth of the second wheel part (the teeth do
not align with one another). The gear wheel may therefore be used
as an idler gear in a gear train so as to reduce backlash or to
compensate for backlash, wherein the tooth load flank change from
the drive wheel to the idler gear and from the idler gear to the
output wheel is taken into account. The tooth flanks of the teeth
of the first wheel part are brought into position with respect to
the load flanks of a drive wheel and an output wheel of the drive
gear so as to transmit a torque from the drive wheel via the idler
gear to the output wheel. The eccentric bearing of the second wheel
part renders it possible for the teeth of the second wheel part and
the first wheel part to be offset with respect to one another in
such a manner that the tooth flanks of the second wheel part come
into engagement with the trailing edges of the drive wheel and the
output wheel.
In particular, the teeth of the first wheel part may be distributed
uniformly over an outer periphery of the first wheel part.
Alternatively or in addition thereto, the teeth of the second wheel
part may be distributed uniformly over an outer periphery of the
second wheel part.
It is preferred that a number of the multiple teeth of the first
wheel part corresponds to a number of the multiple teeth of the
second wheel part.
It is preferred that the multiple teeth of the first wheel part and
the multiple teeth of the second wheel part are constructed in an
identical manner.
In a particularly preferred exemplary embodiment, the second wheel
part may deform in regions in an elastic manner in a radial
direction in relation to the second axis. By way of example, the
second wheel part may be produced in regions from an elastic
material, and may comprise an elastic element and/or an elastic
structure. The elasticity of the second wheel part renders it
possible in combination with the eccentric position of the centre
of rotation of the second wheel part to brace said second wheel
part between the trailing edges of the drive wheel, the trailing
edges of the output wheel and the bearing of the second wheel part.
In addition, the second wheel part may deform in an elastic manner
in order to adjust the positions of the trailing edges of the drive
wheel and output wheel, said positions resulting from the
production tolerances. In particular, the second wheel part is to
not deform in an elastic manner if the sign of the drive torque or
the output torque changes. The goal is to prevent the load flanks
from lifting. This is achieved in that the pre-stressing force from
the eccentric seat of the centre of rotation of the second wheel
part and also the elasticity of said second wheel part compensates
for the negative portion of the torque and therefore at this moment
in time does not lead to an elastic deformation of the second wheel
part or to the load flanks lifting. However, the elasticity of the
second wheel part has a positive effect on the adjustment to the
production tolerances and the backlash that occurs in practice.
Alternatively, this could also be ensured via the screwing
arrangement of the first and the second bearing bolt.
In one exemplary embodiment, the second wheel part may rotate
relative to the first wheel part. In particular, the first wheel
part may be embodied from a solid material.
In one preferred exemplary embodiment, the second wheel part
comprises at least one gear wheel sheet. The at least one gear
wheel sheet may deform in an elastic manner in a radial direction
in relation to the second axis. The use of gear wheel sheets that
comprise by way of example a material thickness of approximately 1
mm renders it possible to integrate the elasticity into the
structure of the gear wheel sheets, for example by means of
providing elongated holes in the gear wheel sheets.
In a further development, multiple gear wheel sheets are provided
that are arranged adjacent to one another and/or form a gear wheel
sheet stack.
It is preferred that the gear wheel sheets may be oriented in such
a manner that they align with one another in an axial
direction.
In a further exemplary embodiment, the second wheel part and/or the
at least one gear wheel sheet are/is produced from a spring steel.
An elasticity may consequently be ensured in regions by means of
providing corresponding structures.
In one embodiment, the at least one gear wheel sheet comprises at
least one elongated hole, preferably multiple elongated holes so as
to provide an elasticity of the second wheel part. The at least one
elongated hole extends in a peripheral direction about the second
axis, in particular in a circular and/or helical manner.
In a further embodiment, the gear wheel comprises a first wheel
stud about which the first wheel part is mounted in a rotatable
manner. Alternatively or in addition thereto, the gear wheel
comprises a second wheel stud about which the second wheel part is
mounted in a rotatable manner. It is preferred that the first wheel
stud and the second wheel stud may be fastened to one another in an
eccentric manner with respect to one another, in particular via a
press fit arrangement.
In a further development the gear wheel comprises a first plain
bearing bush that is arranged between the first wheel stud and the
first wheel part. Alternatively or in addition thereto, the gear
wheel comprises a second plain bearing bush that is arranged
between the second wheel stud and the second wheel part.
In order to lubricate the plain bearing bush, an in particular
central lubrication duct may be provided in the first wheel stud
and/or the second wheel stud. It is preferred that a first radial
duct may extend from the lubrication duct to the first plain
bearing bush and/or a second radial duct may extend to the second
plain bearing bush so as to supply a lubricating fluid. By way of
example, a lubricating fluid may be supplied to the lubrication
duct via ducts in a crankcase of the internal combustion engine. By
way of example, the first radial duct and/or the second radial duct
may be provided in the first wheel stud, between the first wheel
stud and the second wheel stud or in the second wheel stud.
It is also possible that the gear wheel comprises at least one
further wheel part that may be embodied respectively according to
the second wheel part of the idler gear. By way of example, in the
case of multiple output wheels for each output wheel a dedicated
"second" wheel part may therefore be provided.
The invention also relates to a gear train for a motor vehicle. The
gear train comprises an idler gear that is disclosed as a gear
wheel as herein. The gear train comprises a drive wheel that meshes
with the first wheel part of the idler gear and the second wheel
part of the idler gear. The gear train comprises an output wheel
that meshes with the first wheel part of the idler gear and the
second wheel part of the idler gear. The gear train may achieve the
advantages described herein for the gear wheel.
In a preferred embodiment variant, the second wheel part of the
idler gear is braced by the drive wheel, in particular by trailing
edges of the drive wheel, and the output wheel, in particular by
trailing edges of the output wheel, in a direction with respect to
the second axis in particular in an elastic manner.
In a further preferred embodiment variant, load flanks of the drive
wheel and load flanks of the output wheel are in engagement with
the first wheel part. Alternatively or in addition thereto,
trailing edges of the drive wheel and trailing edges of the output
wheel are in engagement with the second wheel part.
In a further embodiment variant, the second axis is arranged offset
in relation to the first axis in a direction of an angle bisector
in relation to an angle that is defined between an axis of rotation
of the drive wheel, of the first axis and an axis of rotation of
the output wheel. This offset arrangement renders it possible that
the tooth flanks of the second wheel part may be brought into
position with respect to the trailing edges both of the drive wheel
as well as the output wheel.
In one embodiment, the multiple teeth of the first wheel part
contact load flanks of the drive gear wheel and load flanks of the
output gear wheel. Alternatively or in addition thereto, the
multiple teeth of the second wheel part contact trailing edges of
the drive gear wheel and trailing edges of the output gear
wheel.
In particular, the load flanks and the trailing edges of the drive
gear wheel may lie opposite one another. The load flanks and the
trailing edges of the output gear wheel may likewise lie opposite
one another.
In a further embodiment, a lifting of the multiple teeth of the
first wheel part from load flanks of the drive wheel and from load
flanks of the output wheel in the case of a change of sign of the
drive torque and/or the output torque and/or in the case of
torsional oscillations is counteracted by means of bracing the
second wheel part, said bracing resulting in particular from the
offset arrangement between the first wheel part and the second
wheel part and an elasticity of the second wheel part.
In one exemplary embodiment, multiple output wheels are provided
that mesh with the idler gear. A further wheel part of the idler
gear is provided for each output wheel, said further wheel part
being embodied in each case corresponding to the second wheel part
of the idler gear.
The invention also relates to a motor vehicle, in particular a
commercial vehicle (for example a truck or an omnibus). The motor
vehicle comprises a gear train as disclosed herein. The motor
vehicle optionally comprises a compressor for compressing air that
is driven via the gear train.
It is also possible to use the gear wheel as disclosed herein
and/or the gear train as disclosed herein in any other machine.
In particular, it is also possible to use the gear wheel as
disclosed herein and/or the gear train as disclosed herein in other
driven units that comprise a torque curve having a change of
sign.
Moreover, the gear wheel as disclosed herein and/or the gear train
as disclosed herein may also be used so as to reduce and/or prevent
a transmission of torsional oscillations of a crank shaft of an
internal combustion engine.
The above-described preferred embodiments and features of the
invention may be combined with one another in an arbitrary manner.
Further details and advantages of the invention are described below
with reference to the attached drawings. In the drawings:
FIG. 1 illustrates a schematic model of a gear train in an exploded
view;
FIG. 2 illustrates a front view of the schematic model of a gear
train;
FIG. 3 illustrates a further front view of the schematic model of a
gear train in the non-mounted state;
FIG. 4 illustrates a front view of an idler gear in accordance with
an exemplary embodiment;
FIG. 5 illustrates a sectional view of the idler gear along a line
A-A in FIG. 4; and
FIG. 6 illustrates an exploded view of the idler gear in accordance
with the exemplary embodiment.
The embodiments that are illustrated in the figures correspond at
least in part with the result that similar or identical parts are
provided with the same reference numeral and with regard to their
explanation reference is also made to the description of the other
embodiments or figures in order to avoid repetitions.
In the FIGS. 1 to 3 a schematic model of a gear train 10 in
accordance with the current disclosure is illustrated in various
views so as to explain the functioning of the gear train 10.
An exemplary construction of the gear train 10 is described below
with reference to FIGS. 1 and 2.
The gear train 10 comprises a drive wheel 12, an idler gear 14 and
output wheel 16. The drive wheel 12 meshes with the idler gear 14
that in turn meshes with the output wheel 16. It is also possible
that multiple output wheels 16 mesh with the idler gear 14.
The drive wheel 12, the idler gear 14 and the output wheel 16 are
mounted respectively on corresponding wheel studs in a rotatable
manner. The wheel studs of the gear wheels 12, 14 and 16 are
fastened by way of example via screws 34 (cf. FIG. 2) on the
crankcase of the internal combustion engine.
The drive wheel 12 is mounted in a rotatable manner on a wheel stud
18 (cf. FIG. 2). The drive wheel 12 may be driven by way of example
by a crankshaft 20 (illustrated schematically in FIG. 2) of an
internal combustion engine of a motor vehicle. The motor vehicle
may be by way of example a commercial vehicle, in particular an
omnibus or a truck. It is also possible that the drive wheel 12 is
driven in another manner.
The output wheel 16 is mounted in a rotatable manner on a wheel
stud 22 (cf. FIG. 2). The output wheel 16 may be used by way of
example so as to drive an auxiliary consumer 24 (illustrated
schematically in FIG. 2) of the motor vehicle. In particular, the
auxiliary consumer 24 may tend towards rotational irregularity and
torsional oscillations in the form of a torque curve having a
change in sign on account of the manner in which said auxiliary
consumer functions and/or on account of the configuration of said
auxiliary consumer.
The auxiliary consumer 24 may be by way of example an oil pump, a
hydraulic pump or an air compressor. The air compressor of a
commercial vehicle conventionally comprises by way of example a
non-uniform output torque having a change of sign that results from
its design. The air compressor may function by way of example
according to the principle of a plunger compressor. Air is drawn in
through an inlet valve of the air compressor, is compressed in a
cylinder of the air compressor by means of a piston of the air
compressor and is pushed out via an outlet valve of the air
compressor. Depending upon the design, residual compressed air
remains in the cylinder after the procedure of pushing air out.
This residual air expands after exceeding the upper dead centre of
a piston movement of the piston and returns energy via drive
kinematics of the air compressor.
Further rotational irregularities and torsional oscillations in the
gear train 10 result by way of example from a non-uniform torque
curve of the crankshaft 20 of the internal combustion engine.
Expressed in simple terms, the cooperation of the gas force in a
cylinder and the mass force of the kinematics results in an
alternating torque curve over the crank angular range 720.degree..
These individual curves are superimposed in the case of
multi-cylinder engines on a total curve that comprises minima and
maxima. The characteristics of this torque curve are by way of
example dependent upon a cylinder number, an ignition pressure and
the combustion.
If countermeasures for reducing or compensating for the backlash
are not undertaken, it is possible on account of the change of sign
of the drive torques and output torques for the load flanks of the
gear wheels of the gear train to lift within the backlash. The
subsequent contact that the tooth flanks make with one another
results in disturbing noises and an increased wear.
The present disclosure compensates for or reduces at least the
backlash between the drive wheel 12 and the idler gear 14 and
between the idler gear 14 and the output wheel 16 with the result
that an increased wear and disturbing noises are prevented or at
least reduced.
For this purpose, the idler gear 14 comprises a first wheel part 26
and a second wheel part 28.
The first wheel part 26 is mounted so that it may rotate about a
first axis A (cf. FIG. 2). The second wheel part 28 is mounted so
that it may rotate about a second axis B (cf. FIG. 2), said axis
being arranged offset and parallel with respect to the first axis
A.
With reference to FIG. 2, it is illustrated that the second axis B
of the second wheel part 28 is arranged in a radial direction of
the first axis A of the first wheel part 26 offset with respect to
the first axis A. Specifically, the second wheel part 28 is offset
along an arrow C. The arrow C extends along an angle bisector. The
angle bisector halves an angle that is defined between an axis of
rotation of the drive wheel 12, the first axis A and an axis of
rotation of the output wheel 16. The angle bisector extends through
the first axis A. As is described in detail below, the second wheel
part 28 is arranged offset with respect to the first wheel part 26
in such a manner that tooth flanks of the second wheel part 28 make
contact with trailing edges of the drive wheel 12 and of the output
wheel 16. The centre of rotation of the first wheel part 26 (axis
A) and the centre of rotation of the second wheel part 28 (axis B)
are offset in the installed state in a radial direction by the
distance of the first axis A with respect to the second axis B. As
a consequence, an offset arrangement is produced in the peripheral
direction between the multiple teeth 36 of the first wheel part 26
and the multiple teeth 42 of the second wheel part 28.
With further reference to FIG. 2, it is illustrated that the first
wheel part 26 in particular is mounted so that it may rotate about
a first wheel stud 30 of the idler gear 14. The first wheel stud 30
comprises the first axis A as a centre axis. The position of the
first axis A and therefore of the first wheel part 26 is oriented
in this case towards the operating pitch circles of the classic
toothing design between the drive wheel 12, the idler gear 14 and
the output wheel 16. The second wheel part 28 is mounted in
particular so that it may rotate about a second wheel stud 32. The
second wheel stud 32 comprises the second axis B as a centre axis.
The first wheel part 26 may rotate relative to the second wheel
part 28.
The first wheel stud 30 and the second wheel stud 32 may be
fastened to one another by means of screws 34. However, by way of
example a press fit arrangement between the wheel studs 30, 32 is
also possible. The screws 34 may fasten the wheel studs 18, 22, 30
and 32 by way of example on a crankcase of the internal combustion
engine.
The first wheel part 26 comprises on an outer periphery of said
wheel part multiple teeth 36 that are distributed uniformly over
the outer periphery. The teeth 36 mesh with teeth 38 of the drive
wheel 12 and with teeth 40 of the output wheel 16. During the
normal operation the drive wheel 12 rotates by way of example
anticlockwise in a direction of rotation D (cf. FIGS. 2 and 3). The
drive wheel 12 drives the idler gear 14. The idler gear 14 rotates
in the clockwise direction. In this case, load flanks 38A of the
teeth 38 of the drive wheel 12 mesh with first load flanks 36A of
the teeth 36 of the first wheel part 26 of the idler gear 14. The
idler gear 14 in turn drives the output wheel 16. The output wheel
16 rotates anticlockwise. In this case, second load flanks 36B,
which lie opposite the first load flanks 36A, of the first wheel
part 26 of the idler gear 14 mesh with load flanks 40A of the
output wheel 16. A backlash occurs between trailing edges 38B of
the drive wheel 12, which lie opposite the load flanks 38A, and the
second load flanks 36B of the first wheel part 26 of the idler gear
14 depending upon the assembly and so that the gear wheels 12, 14
may turn freely. A backlash likewise occurs between trailing edges
40B of the output wheel 16, which lie opposite the load flanks 40A,
and the first load flanks 36A of the first wheel part 26 of the
idler gear 14 depending upon the assembly and so that the gear
wheels 14, 16 may turn freely. This backlash may be compensated for
or at least clearly reduced by means of the second wheel part 28 of
the idler gear 14.
The second wheel part 28 comprises on an outer periphery of said
wheel part multiple teeth 42 that are distributed uniformly over
the outer periphery. The second wheel part 28 is braced between the
drive wheel 12, the output wheel 16 and the second wheel stud 32 in
such a manner that first tooth flanks 42A of the teeth 42 of the
second wheel part 28 of the idler gear 14 mesh with the trailing
edges 38B of the teeth 38 of the drive wheel 12. Moreover, second
tooth flanks 42B of the teeth 42 of the second wheel part 28 of the
idler gear 14 mesh with the trailing edges 40B of the teeth 40 of
the output wheel 16.
The second wheel part 28 comprises an elastic region 44. The
elastic region 44 may be embodied by way of example by means of
elongated holes that extend by way of example in a helical manner
about the second axis B. The second wheel part 28 may be produced
by way of example from spring steel. The second wheel part 28 may
deform in regions in an elastic manner in a radial direction
towards the second axis B on account of the elastic region 44.
As has been explained above in detail, the centre of rotation of
the second wheel part 28 may be arranged in an eccentric manner
with respect to the centre of rotation of the first wheel part 26.
Moreover, the second wheel part 28 may deform in regions in an
elastic manner. The pre-stressing force, which is generated by
means of the eccentricity and the elasticity of the second wheel
part 28, between the second wheel part 28 on one hand and the drive
wheel 12 and output wheel 16 on the other hand prevents the load
flanks of the gear wheels 12, 14 and 16 from lifting. As a
consequence, undesired acoustic emissions and increased wear on the
tooth flanks may be avoided. In other words, the idler gear 14 may
compensate for the effects of the backlash on the drive wheel 12
and on the output wheel 16 in the case of a corresponding design by
means of the second wheel part 28 being offset in an eccentric
manner. The pre-stressing force is ensured by means of the
elasticity at the second wheel part 28 and also the eccentric
offset arrangement of the centre of rotation of the second wheel
part 28 relative to the first wheel part 26 and it is necessary in
order to avoid lifting at the load flanks. The magnitude of the
bracing arrangement of the second wheel part 28 may be realised and
may be set by means of the eccentricity and/or the elasticity of
the second wheel part 28. These parameters are dimensioned in
dependence upon the magnitude of the backlash between the meshing
wheels 12, 14 and 16 and the negative portions of the torque that
is to be transmitted.
Reference is made to the fact that the eccentricity of the centre
of rotation of the second wheel part 28 in relation to the centre
of rotation of the first wheel part 26 (in other words that the
axes A and B are offset parallel with respect to one another) is
necessary so that the tooth flanks 42A of the second wheel part 28
lie against the trailing edges 38B of the drive wheel 12 and
simultaneously the tooth flanks 42B of the second wheel part 28 lie
against the trailing edges 40B of the output gear wheel 16. This
function would not be possible to realise with a second wheel part
that is mounted in a concentric manner with respect to the first
wheel part. In the case of a bracing arrangement in the form of a
rotation in the peripheral direction of a second wheel part that is
mounted in a concentric manner with respect to the first wheel
part, only one of the tooth flanks of the second wheel part would
come into contact with a trailing edge of the drive wheel (or the
output wheel). The other tooth flank of the second wheel part would
in contrast come into contact with a load flank of the output wheel
(or the drive wheel) on account of the change of flank.
An exemplary embodiment of the idler gear 14 is described below
with reference to the FIGS. 4 to 6, said idler gear being based
upon the model of the gear train 10 that is described with
reference to the FIGS. 1 to 3.
The idler gear 14 comprises the first wheel part 26 and the second
wheel part 28. The first wheel part 26 is mounted via a first plain
bearing bush 46 in a rotatable manner on the first wheel stud 30.
The second wheel part 28 is mounted via a second plain bearing bush
48 in a rotatable manner on the second wheel stud 32. The first
wheel part 26 and the second wheel part 28 may rotate relative to
one another. The offset arrangement of the teeth 36 of the first
wheel part 26 and the teeth 42 of the second wheel part 28 and also
the eccentric arrangement of the centre of rotation of the second
wheel part 28 in relation to the centre of rotation of the first
wheel part 26 are barely visible in typical application examples,
as is illustrated in the exemplary embodiments shown in FIGS. 4 and
6.
In the exemplary embodiment the first wheel part 26 is embodied
from a solid material. The second wheel part 28 is formed from a
stack of multiple (eight in the exemplary embodiment) gear wheel
sheets 50 that are arranged adjacent to one another. The gear wheel
sheets 50 may comprise by way of example a material thickness of 1
mm. The gear wheel sheets 50 are oriented in an axial direction in
alignment with one another. The gear wheel sheets 50 may deform in
an elastic manner in a radial direction in relation to an axis of
rotation of the second wheel part 28. The gear wheel sheets 50
comprise multiple elongated holes 44 so as to provide the
elasticity of said gear wheel sheets 50. The elongated holes 44
extend in a circular or helical manner in a peripheral direction
about the axis of rotation of the second wheel part 28. In
particular, the gear wheel sheets 50 may be produced from a spring
steel.
In addition, the idler gear 14 comprises a thrust washer 52. The
wheel studs 30, 32 may be fastened via multiple screws (not
illustrated) on a crankcase of the internal combustion engine. The
wheel studs 30, 32 may be fastened to one another via a press fit
arrangement. The thrust washer 52 may sit with a press fit
arrangement on the second wheel studs 32. As a consequence, the
idler gear 14 may be mounted as one unit. The thrust washer 52
supports the gear wheel sheets 50 axially and therefore prevents
the gear wheel sheets 50 from bending.
The plain bearing bushes 46, 48 may be embodied as a hydrodynamic
plain bearing that must be supplied with sufficient lubricating
fluid during operation. The lubricating fluid may be supplied from
a central lubricating fluid duct 54 in the first and second wheel
studs 30, 32 via radial ducts in the wheel studs 30, 32 to the
plain bearing bushes 46, 48.
The invention is not limited to the preferred exemplary embodiments
described above. On the contrary, a plurality of variants and
modifications are possible that likewise make use of the inventive
idea and consequently are included in the scope of protection. In
particular, the invention also claims protection for the subject
matter and the features of the dependent claims independently of
the claims that are included by reference. In particular, the
features of the dependent claims are also disclosed independently
of all the features of the independent Claim 1 and by way of
example independently of the features in relation to the presence
and the configuration of the first wheel part and/or the second
wheel part of the independent Claim 1.
LIST OF REFERENCE NUMERALS
10 Gear train 12 Drive wheel 14 Idler gear 16 Output wheel 18 Wheel
stud 20 Crankshaft 22 Wheel stud 24 Auxiliary consumer 26 First
wheel part 28 Second wheel part 30 First wheel stud 32 Second wheel
stud 34 Screw 36 Teeth 36A First load flank 36B Second load flank
38 Teeth 38A Load flank 38B Trailing edge 40 Teeth 40A Load flank
40B Trailing edge 42 Teeth 42A First tooth flank 42B Second tooth
flank 44 Elastic region (elongated holes) 46 First plain bearing
bush 48 Second plain bearing bush 50 Gear wheel sheet 52 Thrust
washer 54 Lubricating fluid duct A First axis B Second axis C Arrow
along the angle bisector D Rotation direction
* * * * *